天山南麓山前平原土壤盐分空间异质性对植物群落组成及结构的影响   总被引：1，自引：1，他引：1  

赵振勇  王让会  尹传华  王雷 《干旱区地理》2007,30(6):839-845

将轮台天山南麓山前平原中下部自北至南分为4个地貌带:洪水剥蚀带、溢出带、三角洲带及两河交汇区带。并以土壤电导作为积盐程度的指标,分析了天山南麓山前平原4个地貌带土壤盐的分布特征:溢出带和三角洲带土壤盐分含量高,两端洪水剥蚀带和两河交汇区带盐分含量低。物种多样性及物种组成分析结果表明,自北至南物种多样性及物种数量都在下降,洪水剥蚀带主要为柽柳群落、琵琶柴群落,溢出带主要为柽柳群落、盐节木群落、盐角草群落,三角洲带及两河交汇区均为柽柳群落。通过相关性分析,土壤盐分与群落物种多样性相关性不显著。但是,土壤盐渍化的变化明显影响到植物群落物种组成的变化、群落类型的空间分布和演替。  相似文献   

The deep-lake deposit in the Upper Triassic Yanchang Formation in Ordos Basin, China and its significance for oil-gas accumulation     

CHEN QuanHong  LI WenHou  GAO YongXiang  GUO YanQin  FENG JuanPing  ZHANG DaoFeng  CAO HongXia  LIANG JiWei 《中国科学D辑(英文版)》2007,50(Z2):47-58

The deep-lake facies of the Yanchang Formation represents a large outflowing lake basin in the Ordos area. Its deposition can be divided into four stages lake genetic and expanding stage, peak stage, inversion stage and dying stage. All the stages are obviously consistent with the evolution of depositional environment and the paleoclimate in the region. The study indicates that the lake basin has evolution fluctuations from highstand to lowstand for four times in its evolution history, and the deposition center of the lake has not obviously moved, staying along the Huachi-Yijun belt. The deep lake sedimentary system mainly consists of deep water deltas and turbidite fans during the entire evolution course of the lake basin in the Late Triassic. The former mainly developed on the slope of steep shore of the delta in the early period of the deep-water expansion and gradually experienced a big shift from deep-water deltas to shallow-water platform delta. And the latter appeared almost in all the above stages and had two types of turbidite fans, slope-moving turbidite fans and slump turbidite fans. The slope-moving turbidite fans have relatively complete facies belts overlapping one another vertically and consist of the slope channel of inter fans, the turbidite channel, inter turbidite channel and turbidite channel front of middle fans and outer fans (or lakebottom plain). However, the slide-moving turbidity fans are formed in the deep lake with their microfacies difficult to be distinguished, and only the center microfacies and edge microfacies can be determined. The two types of the turbidity fans are similarly distributing in the near-root-slope and far-root-slope regions. The deep-lake deposition governs the distribution of the hydrocarbon and reservoir, while the slope-moving turbidite fans are excellent reservoirs for oil-gas exploration due to their great thickness, widespread distribution and accumulation properties.  相似文献   

土地覆被变化对陆地碳循环的影响—以黄河三角洲河口地区为例   总被引：11，自引：1，他引：11  

王绍强  许珺  周成虎 《遥感学报》2001,5(2):142-148

土地利用/土地覆被变化是全球变化研究的重点，是影响陆地碳循环的一个重要因子。该文对黄河三角洲河口地区1992年和1996年9月份的TM影像进行非监督分类，做出该地区土地覆被类型分布图，以及估算土地覆被类型的变化面积，计算结果显示1992年该研究地区植被碳库和土壤碳库分别为11.43×10  相似文献   

黄河、辽河三角洲农业发展的比较研究   总被引：1，自引：0，他引：1  

许学工  林辉平  后立胜 《地域研究与开发》2001,20(1):70-74

黄河三角洲和辽河三角洲是中国北方两个有代表性的大河三角洲，通过比较农业发展的自然条件，结构状况，历史和发展趋势，分析了它们的共性和差异，在此基础上提出了中国北方三角洲实现农业可持续发展的途径；通过水土整治工程，形成农业可持续发展的环境条件和基础设施，通过生态农业和生态工程，形成农业可持续发展的技术模式和良性循环，通过结构调整和农村经济社会的发展，形成农业可持续发展的宏观调控和支持保障系统。  相似文献   

Assessment of coastal vulnerability to environmental change in Jiangsu coastal plain     

YANG Gui-shan  SHI Ya-feng  ZHANG Chen  LIANG Hai-tang 《地理学报(英文版)》2001,11(1):24-33

1 IntroductionCoastal areas, with dense population and high urbanization, are highly sensitive to global environmental change. The impacts of coastal environmental changes, such as sea level rise and related disasters exacerbation on socio-economic development of coastal areas, have become a matter of public concern. To study the vulnerable scope and degree of impacts of sea level rise and related exacerbating coastal hazards can provide a scientific basis for lessening the potential losses th…  相似文献   

鼎湖山自然保护区大气气溶胶中的PAHs   总被引：6，自引：2，他引：6  

祁士华  叶兆贤等 《地球科学》2001,26(1):83-87

多环芳烃（PAHs)是环境中分布广泛、危害人类健康的有机化合物，通过对鼎湖山自然保护区自然地理和大气气溶胶中苯并（a)芘分析认为，春季样品中大气气溶胶中PAHs主要来源于高等植物排放，夏季来源于珠江三角洲经济区化石燃烧排放。  相似文献   

珠江三角洲软土微结构的定量研究   总被引：4，自引：0，他引：4  

李榴芬  彭元贵 《华东地质学院学报》2001,24(2):127-130

对用不同长度的PVC管在珠海和广州两地采得的淤泥样柱施于一定荷载，然后在扫描电镜下研究软土受压后在样柱垂深方向上的微结构变化，并将样品的微结构照片扫描，在计算机内进行量化处理。结果表明，样品的孔隙分布分维差随着离施压点距离的增加而逐渐减小，从而得到两者的关系方程。据此，可了解在一定荷载下应力在软土层中向下的衰减趋势。文章还对软土的天然含水量和围压对压缩变形的影响作了初步的讨论。  相似文献   

江汉平原多目标地球化学调查主要成果与意义   总被引：11，自引：6，他引：11  

张德存  张宏泰 《中国地质》2001,28(12):1-4,21

介绍了覆盖区多目标地球化学调查江汉平原武汉试点区所取得的阶段性成果。共归纳出在土壤地球化学图件编制和在第四纪地质、土壤类型及分布、土壤环境状况、农业土壤利用地球化学解释5个方面的成果，从而以实际材料论证了覆盖区多目标地球化学调查在查明我国土壤资源与环境方面的重要作用以及在社会经济生活中的实际意义。  相似文献   

The Upper Permian Sedimentary Facies and Its Role in the Dajing Cu-Sn Deposit, Linxi County, Inner Mongolia, China   总被引：3，自引：1，他引：3  

Gongjiong QIN  Yosuke KAWACHI  Liqing ZHAO  Yongzheng WANG  Qiang OU 《Resource Geology》2001,51(4):293-305

Abstract: Exhaustive investigations were launched for confirming the upper Permian host rocks of the Dajing Cu-Sn Deposit, probing into the possibility that Dajing is a Sedex type deposit during cosedimentation, complementing the deficiency of previous researches and going further into substantiating the role of the upper Permian strata in the control of ore distribution. After more than two years work, we reclassified the sedimentary facies in the Dajing area and its periphery as shallow fresh water lake and delta. Indicative sedimentary structures, such as ripple marks, rain marks, and mud cracks combined with contemporary fossils, were revealed. Having measured the flow directions, performed chemical comparison, and analyzed various sediments from sourceland in the Dajing area by XRF, we consequently redivided the strata into four sedimentary members, among which P₂l₁ and P₂l₂ were concluded as significant ore-hosted strata. The upper Permian basin was a lateral rift basin. The water and sediments in the basin are much deeper and thicker in the north than those in the south.
The indicators of special sedimentary facies, such as gravity flow, brine pool and synchronogenic stratiform structure of the ore cannot be found in the Dajing area. There was no growth fault, assemblage of sulfide and sulfate, and no zonation as well.
On the basis of study in this area, taking into account the paleosedimentary environment as capriciously flowing shallow lake, which approximated the state of oxidation, we figured that the paleogeography made it prohibitively difficult to form stratiform sulfide deposits which are prone to form in deoxidized environment. It can be ruled out the possibility that the Dajing deposit is a syngenetic deposit during sedimentation.  相似文献   

蒲江—新津—成都—德阳断裂带——成都平原内一条代表性弱活动地震带的地震地质特征     

钱洪  唐荣昌  马声浩 《四川地震》1992,(4)

活断层是地震的潜在策源地。然而不同的活断层上地震潜在能力有极大的差别。客观地评价活断层上地震潜在能力不仅是地震预报研究的需要,对国民经济建设的布局和抗震决策也极为重要。在这个意义上,对弱活动性断裂的研究与对强活动性断裂的研究具有同样的重要性。本文以弱活动的蒲江—新津—成都—德阳断裂带为例,讨论了该断裂的晚第四纪活动性,断裂带的地质结构以及断裂的切割深度等因素对该断裂带地震潜在能力的可能影响。  相似文献